Output Register Information

When control returns to the caller, the GPRs contain:

Register

Contents

0

Reason code if the return code in GPR 15 is not 0, otherwise, used as a work register by the system.

1

Used as a work register by the system.

2 - 13

Unchanged

14

Used as a work register by the system.

15

Return code

When control returns to the caller, the ARs contain:

Register

Contents

0 - 1

Used as a work register by the system.

2 - 13

Unchanged

14 - 15

Used as a work register by the system.

Some callers depend on register contents remaining the same before and after issuing a service. If the system changes the contents of registers on which the caller depends, the caller must save them before issuing the service, and restore them after the system returns control.